High-Strength Bainitic Steels

Document Type : Research Paper

Authors

1 Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalúrgicas (CENIM), Spain

2 Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.

Abstract

With careful design, mixed microstructures consisting of fine plates of upper bainitic ferrite separated by thin films of stable retained austenite have exhibited impressive combinations of strength and toughness in highsilicon bainitic steels. The silicon suppresses the precipitation of brittle cementite leading to an improvement in toughness. The essential principles governing the optimisation of such microstructures are well established, particularly that large regions of unstable high-carbon retained austenite must be avoided. The aim of the present work was to see how far these concepts can be extended to achieve the highest ever combination of strength and toughness in bulk-samples, consistent with certain hardenability and processing requirements.

Keywords


H. K. D. H. Bhadeshia: Acta Metall., 29(1981),
1117.
[2] H. K. D. H. Bhadeshia and A. R. Waugh: Acta
Metall., 30(1982) 775.
[3] L. C. Chang and H. K .D. H. Bhadeshia: Mater.
Sci. Eng., 1994, A184, L17-20.
[4] I. Stark, G. D. W. Smith and H. K. D. H.
Bhadeshia: in ‘Solid→Solid Phase Transformations’,
ed. By G. W. Lorimer, Institute of Metals, London
(1988), 211.
[5] H. K. D. H. Bhadeshia and D. V. Edmonds: Metal
Sci., 17(1983), 411.
[6] H. K. D. H. Bhadeshia and D. V. Edmonds: Metal
Sci., 17(1983), 420.
[7] H. K. D. H. Bhadeshia and D. V. Edmonds: Acta
Metall., 28(1980), 1265.
[8] H. K. D. H. Bhadeshia: Metal Sci., 16(1982), 159.
[9] V. T. T. Miihkinen and D. V. Edmonds: Mater.
Sci. Technol., 3(1987), 422.
[10] V. T. T. Miihkinen and D. V. Edmonds: Mater.
Sci. Technol., 3(1987), 432.
[11] V. T. T. Miihkinen and D. V. Edmonds: Mater.
Sci. Technol., 3(1987), 441.
[12] Defence Evaluation Research Agency Technical
Note, DRA/WSS/WT6/CR/93 2/1.0.
[13] N. Chester and H. K. D. H. Bhadeshia: Journal
de Physique IV, 7(1997), 41.
[14] S. J. Jones and H. K. D. H. Bhadeshia: Acta
Mate., 45(1997), 2911.
[15] J. Durnin and K. A. Ridal: Iron and Steel Inst.,
206(1968), 60.
[16] M. J. Dickson: J. Appl. Cryst., 2(1969), 176.
[17] D. J. Dyson and B. Holmes: Iron and Steel Inst.,
208(1970), 469.
[18] G. F. Vander Voort: ‘Metallography. Principles
and Practice’, McGraw-Hill, New York, (1984), 427.
[19] L. C. Chang: Metall. Trans., 30A(1999), 909.
[20] K. J. Irvine, F. B. Pickering, W. C.
HESELWOOD and M. J. ATKINS: J. iron Steel
Inst., 195(1957), 54.
[21] A. P. Coldern, R. L. CRYDERMAN and M.
SEMCHYSHEN: Steel Strengthening Mechanisms,
17; 1969, Ann Arbor, USA, Climax Molybdenum.
[22] B. P. J. SANDVIK and H. P. NEVALAINEN:
Met. Tech., 15(1981), 213.